Most of these residents are also old. It's literally the boomer generation fucking over everyone trying to move in for their own benefit.
And ignore all the environmental bullcrap that existing home owners will try to astroturf. People won't hurt environment by gathering in one place that they did by spreading up.
The job growth is in knowledge, which benefits from being close by. For example, last week I walked from the office to Eventbrite to learn what they're doing. No way you're getting the same benefit from watching a video. To promote the best opportunities, we're going to have to reform our existing cities.
If you're trying to build a new community, it's going to require some other benefit. Like Peter Thiel and his seasteading.